Adjusting the targeted number of transmission attempts

ABSTRACT

The invention is directed towards a method and transmission attempt determining device for adjusting the targeted number of transmission attempts in uplink communications between mobile stations and a cell in a wireless network handled by a cell handling device. According to the invention measurement data (RC) of radio conditions and service requirement data (SR) of the uplinks for mobile stations are obtained ( 36, 38, 40 ). Based on this data a determination ( 42 ) is made if the targeted number of transmission attempts should be adjusted. If a change should be made ( 42 ) an increase or a decrease is then determined ( 44 ) and the targeted number of transmission attempts are adjusted in the selected direction ( 46 ).

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of mobile station powercontrol and resource management in wireless networks. The invention moreparticularly relates to a method of adjusting the targeted number oftransmission attempts in uplink communications between at least onefirst group of mobile stations including at least one mobile station anda cell in a wireless network handled by a cell handling device as wellas to a transmission attempt determining device for a cell in a wirelessnetwork that is handled by a cell handling device, which cell handlingdevice handles communication with at least one first group of mobilestations including at least one mobile station.

DESCRIPTION OF RELATED ART

In a typical cellular radio system, mobile user equipment units (UEs)communicate via a radio access network (RAN) to one or more corenetworks. The user equipment units (UEs) can be mobile stations such asmobile telephones (“cellular” telephones) and laptops with mobiletermination, and thus can be, for example, portable, pocket, hand-held,computer-included, or car-mounted mobile devices which communicate voiceand/or data with radio access network.

The radio access network (RAN) covers a geographical area which isdivided into cell areas, with each cell area being served by a basestation. A cell is a geographical area where radio coverage is providedby the radio base station equipment at a base station site. Each cell isidentified by a unique identity, which is broadcast in the cell. Thebase stations communicate over the air interface (e.g., radiofrequencies) with the mobile user equipment units (UE) within range ofthe base stations. In the radio access network, several base stationsare typically connected (e.g., by landlines or microwave) to a radionetwork controller (RNC). The radio network controller, also sometimestermed a base station controller (BSC), supervises and coordinatesvarious activities of the plural base stations connected thereto.

One example of a radio access network is the Universal MobileTelecommunications (UMTS) Terrestrial Radio Access Network (UTRAN). TheUMTS is a third generation system which in some respects builds upon theradio access technology known as Global System for Mobile communications(GSM). UTRAN is essentially a radio access network providing widebandcode division multiple access (WCDMA) to user equipment units (UEs). TheThird Generation Partnership Project (3GPP) has undertaken to evolvefurther the UTRAN and GSM-based radio access network technologies.

In a WCDMA system there are basically two types of power controlalgorithms; inner and outer-loop power. The inner-loop power control,which is fast, adjusts the transmit power of a sending entity towards aspecific signal-to-carrier ratio (SIR) target at a receiving entity,whereas the outer-loop power control (OLPC), which is slow, adjusts theSIR target of the inner loop power control in order to maintain aspecified quality-based target. In the uplink, i.e. from mobile stationto base station, OLPC is used both for DCH (Dedicated Channel) and E-DCH(Enhanced Data Channel) channels, but in a slightly different manner.Due to the use of HARQ (Hybrid Automatic Repeat Request) protocol in EUL(Enhanced Uplink), the currently used OLPC quality target is the numberof transmission attempts.

It is expected that EUL will eventually replace ordinary so-called R99uplink solutions, at least in hot spots. Such examples might be thatVoIP (Voice over IP) replaces CS (Circuit-Switched) speech and thatservices requiring higher bit rates are/will be deployed on E-DCHinstead of R99 DCHs. However, to make this scenario happen, the capacityand coverage for e.g. a VoIP solution must be equally efficient as CSspeech, and higher bit rate services deployed on EUL must outperformtheir R99 counterparts.

For some radio access bearer realizations in 3GPP (3^(rd) GenerationPartnership Project) WCDMA (Wideband Code Division Multiple Access)systems, such as E-DCH and HS-DSCH (High Speed Downlink Shared Channel),HARQ protocols are used to improve the link layer performance. The HARQprotocol enables many transmission attempts to be used to transmit onedata block. Using many transmission attempts, a delay will be added tothe total end-to-end delay for the transmission of the data block.Depending on the service type and the corresponding delay requirements,such extra delay might be considerable. However, it is possible totarget different number of transmission attempts, and by using fewertransmission attempts, a shorter delay will be experienced. This meansthat few transmission attempts are desirable for delay sensitiveservices such as VoIP.

However, for the time being, irrespectively of the rather differentradio conditions, the state of the art is to use a static transmissionattempt target value within the entire cell, e.g. the same transmissionattempt target value for all users in the cell. The problem with this isthat the network does not adapt to different conditions in the cell,i.e. it is not using the scarce UE uplink power efficiently and/oradapts to the uplink interference, and in the end wastes system capacityand/or provides a lower quality than necessary. Hence, a compromise isneeded to provide good enough coverage, user throughput and delay.

Further on, the current OLPC concept is not flexible enough to handledifferent services with different delay and bit rate requirements forvarious radio conditions and cell deployments.

To summarize: According to the state of the art the transmission attempttarget is fixed for each radio bearer (e.g. the Interactive, VoIP).

This means that:

If high transmission attempt target:

-   -   More retransmissions    -   Higher delay    -   More HARQ gain    -   Higher capacity    -   Possibly more stable system

If low transmission attempt target:

-   -   Fast SIR target increase    -   Fewer retransmissions    -   Less HARQ gain    -   Lower delay    -   Lower capacity

There is therefore a need for an improvement in the field oftransmission attempts.

SUMMARY OF THE INVENTION

The present invention is therefore directed towards providing animproved and flexible determination of the targeted number oftransmission attempts by mobile stations communicating with a cellhandling device in a wireless network.

This is generally solved through obtaining measurement data of radioconditions and service requirement data of the uplinks for mobilestations. Based on this data a determination is made concerning if thetargeted number of transmission attempts should be adjusted. If a changeshould be made an increase or a decrease is then determined and thetargeted number of transmission attempts are adjusted in the selecteddirection.

One object of the present invention is thus to provide a method ofadjusting the targeted number of transmission attempts in uplinkcommunications between at least one first group of mobile stationsincluding at least one mobile station and a cell in a wireless network,which method provides an improved and flexible determination of thetargeted number of transmission attempts.

This object is according to a first aspect of the present inventionachieved through a method of adjusting the targeted number oftransmission attempts in uplink communications between at least onefirst group of mobile stations including at least one mobile station anda cell in a wireless network. The method includes the steps: obtainingmeasurement data of the radio conditions of the uplinks between themobile stations of the group and said cell, obtaining servicerequirement data for mobile stations of this group and determining,based on the obtained data, whether the targeted number of transmissionattempts that can be made by mobile stations in the group should beadjusted or not in order to obtain a desired link quality for eachuplink connection. In case the determination indicates that anadjustment should be made it is then determined, based on the obtaineddata, if an increase or a decrease of the targeted number oftransmission attempts should be made, and then the targeted number oftransmission attempts are adjusted in the direction of this latterdetermination.

Another object of the present invention is to provide a transmissionattempt determining device for a cell in a wireless network that ishandled by a cell handling device, which device provides an improved andflexible determination of the targeted number of transmission attempts.

This object is according to a second aspect of the present inventionachieved through a transmission attempt determining device for a cell ina wireless network, where at least one first group of mobile stationsincluding at least one mobile station is communicating with the cell.The transmission attempt determining device comprises a radio conditionmeasurement obtaining unit configured to obtain measurement data of theradio conditions of the uplinks between the mobile stations of the groupand said cell, a service requirement obtaining unit configured to obtainservice requirement data for mobile stations of said the group, and atransmission attempt determining unit. The transmission attemptdetermining unit is here configured to determine, based on the obtaineddata, whether the targeted number of transmission attempts that can bemade by mobile stations in the group should be adjusted or not in orderto obtain a desired link quality for each uplink connection. In case thedetermination indicates that an adjustment should be made it furthermoredetermines, based on the obtained data, if an increase or a decrease ofthe targeted number of transmission attempts should be made and suppliesa control signal indicative of the determined targeted number ofattempts.

The present invention has many advantages. It provides a flexible way ofdetermining how many transmission attempts are to be provided to amobile station. This may furthermore be done according to each singlemobile station, according to different groups of mobile stations, wherea group can be based on service requirements and type of communication,or for all mobile stations, The invention allows several differentaspects to be considered, like cell load, power used, distance to cellhandling device, desirable bit rate and delay.

It should be emphasized that the term “comprises/comprising” when usedin this specification is taken to specify the presence of statedfeatures, integers, steps or components, but does not preclude thepresence or addition of one or more other features, integers, steps,components or groups thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in more detail in relationto the enclosed drawings, in which:

FIG. 1 schematically shows an access network connected to a core networkas well as a mobile station connected to a cell handled by a cellhandling device of the access network,

FIG. 2 shows a block schematic of a transmission attempt determiningdevice according to the present invention being connected to a cellhandling device,

FIG. 3 shows a block schematic of a transmission attempt determiningdevice according to the present invention,

FIG. 4 shows a flow chart of a number of general method steps takenaccording to the present invention in order to adjust the targetednumber of transmission attempts

FIG. 5 shows a flow chart of a number of method steps taken according toa first variation of the present invention in order to adjust thetargeted number of transmission attempts, and

FIG. 6 shows a flow chart of a number of method steps taken according toa second variation of the present invention in order to adjust thetargeted number of transmission attempts.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following description, for purposes of explanation and notlimitation, specific details are set forth such as particulararchitectures, interfaces, techniques, etc. in order to provide athorough understanding of the present invention. However, it will beapparent to those skilled in the art that the present invention may bepracticed in other embodiments that depart from these specific details.In other instances, detailed descriptions of well known devices,circuits, and methods are omitted so as not to obscure the descriptionof the present invention with unnecessary detail.

The present invention is directed towards providing differentiatedtargeted numbers of transmission attempts in a cell of a wirelessnetwork, like a wide area network in the form of a WCDMA network.

As mentioned above, in order to obtain a link quality, which is hereprovided in the form of a signal-to-carrier ratio (SIR), the currentpractice is to set a more or less fixed targeted number of transmissionattempts, also denoted TA target, for a cell. This is impractical,because nowadays there are different services provided that havedifferent requirements regarding for instance bit rate and delay. Thismeans that it would be beneficial to provide different such targets fordifferent types of services. Further information that it would beadvantageous to consider are the load of the cell, i.e. how many mobilestations are communicating with a cell, transmission power, where in acell a mobile station may be provided as well as the servicerequirements of the mobile station. All these different aspects giverise to situations where it would be profitable to use differentiatedtargets.

The present invention will now be described in more detail in thenon-limiting, example context of a Universal Mobile Telecommunications(UMTS) network shown in FIG. 1. A core network CN has a firstconnection-oriented service node 20, which may be a Mobile SwitchingCentre (MSC) that provides circuit-switched services. The core networkCN also includes a second General Packet Radio Service (GPRS) node 21tailored to provide packet-switched type services, which is sometimesreferred to as the serving GPRS service node (SGSN). The service node 20may be connected to circuit switched networks such as PSTN (PublicSwitched Telephone Network) or GSM (Global System for Mobilecommunication). The node 21 may be connected to connectionless-orientednetworks such as the Internet.

Each of the core network service nodes 20 and 21 connects to an accessnetwork AN, which is here a UMTS Terrestrial Radio Access Network(UTRAN). UTRAN AN includes one or more radio network controllers (RNC),where only one RNC 18 is shown in FIG. 1. The RNC 18 is connected to aplurality of cells. The RNC 18 is connected to a first cell handlingdevice 10, a second cell handling device 12 and a third cell handlingdevice 14. Each of these cell handling devices 10, 12 and 14 controlcommunication within a cell. Here it should be realised that one cellhandling device may handle more than one cell. In the figure only a cellassociated with the first cell handling device 10 is shown. The cellsare provided in a geographical area covered by the access network AN.The cell handling devices are within these types of networks basestations. In FIG. 1 one user equipment unit in the form of a mobilestation 16 is shown in the cell handled by the base station 10 in theaccess network AN and shown as communicating with this base station 10.It should be realised that normally there may be provided several mobilestations communicating with a base station.

FIG. 2 shows a block schematic of a transmission attempt determiningdevice 22 according to the present invention being connected to a basestation 10 (indicated with a dashed box). In the drawing only the partsof the base station 10 that are relevant to the present invention areshown. It should be realised that it may include several more entitiesthan the ones shown and to be described here. The base station 10includes one or more antennas for communicating with the mobile station16. However in the figure there is only shown one such antenna. Thisantenna is connected to an output of an inner-loop power control unit28, which has an input that in turn is connected to an output of aSIR-filtering device 26 via a first adding element. The SIR-filteringdevice is in this case in the form of an outer-loop power control unit26. The antenna is also connected to this first adding element. Theinput of the outer loop power control unit 26 is in turn connected to asecond adding element. The antenna is also connected to this secondadding element. The second adding element is furthermore connected tothe output of the transmission attempt determining device 22 accordingto the present invention, which supplies a control signal C to thissecond adding element. The transmission attempt determining unit 22furthermore has an input on which it receives input data D that is usedfor adjusting transmission attempts in line with the principles of thepresent invention. This data D is normally obtained from the basestation 10, which in turn may receive most of this data from thedifferent mobile stations 16 connected to it. However some may also bereceived from the radio network controller of FIG. 1 or the base station10 may gather some of it itself. The outer-loop power control unit hasbeen described as being provided in the base station 10. However, it mayjust as well be provided in the radio network controller. As analternative to OLPC it is also possible to perform some kind of suitableSIR-filtering (signal-to-carrier ratio).

In operation the inner-loop power control unit 28 adjusts the transmitpower of the sender towards a specific link quality target at thereceiver. The link quality is here provided in the form of asignal-to-carrier ratio (SIR). The outer-loop power control unit (OLPC)26 adjusts the SIR target of the inner loop power control unit 28 inorder to maintain a specified quality-based target. The outer-loop powercontrol for uplink channels adjusts the uplink SIR-target so that agiven quality target is fulfilled. The quality target is the fraction ofblocks that is expected to need more than targeted TAs to besuccessfully decoded. If a block is correctly decoded by the basestation and the used number of transmission attempts is higher than thetarget, an OLPC up-step is initiated. If the transmission is notsuccessfully decoded after for instance three transmissions, the SIRtarget is increased by e.g. 0.5 dB. For every successfully decodedtransmission, the corresponding SIR target is decreased by a factorinversely proportional to the error probability, e.g. about 0.01 dB ifthe error rate is 2%. The outer loop power control unit 26 here operatesaccording to HARQ (Hybrid Automated Repeat Request).

The maximum target number of transmission attempts is denoted TA_(max),acceptable for a service. Implicitly, TA_(max) sets limits on the areacoverage for that service as well, so it will be beneficial to havedifferent TA_(max) for services such as VoIP (Voice over IP) and FTP(File Transfer Protocol). A service cannot be given a higher TA targetthan TA_(max).

According to the present invention this target is varied by the device22.

FIG. 3 shows a block schematic of a general structure of thetransmission attempt determining device 22 according to the presentinvention. It includes a radio condition measurement obtaining unit 30receiving measurement data RC of the radio conditions of the uplinksbetween the mobile stations and the cell and a service requirementobtaining unit 32 receiving service requirement data SR for the mobilestations of the cell. The measurement data can be obtained from both themobile stations and the base station. The data D in FIG. 2 is thus madeof the radio condition data RC and the service requirement data SR.Finally there is a transmission attempt determining unit 34, whichreceives the different types of data RC and SR and determines a controlsignal C that indicates a determined targeted number of attempts or achange of the determined targeted number of attempts that is to besupplied to the outer-loop power control unit for the base station.

Now will follow a first general description of the operation of thetransmission attempt determining device with reference being made toFIGS. 3 and 4, where the latter shows a flow chart of a number ofgeneral method steps taken according to the present invention in orderto adjust the targeted number of transmission attempts.

The radio condition measurement obtaining unit 30 of the transmissionattempt determining device 22 first obtains radio condition measurementdata. This data is normally transmission power data, i.e. transmissionpower used by a mobile station, and here in the form of code powermeasurement data, step 36, that is obtained either from the mobilestation or the base station. This step is optional and as an alternativeto code power it is also possible to obtain other types of transmissionpower data, for instance measurements of the power headroom, i.e. theremaining power left to use in the mobile station. Other types of datathat can be measured are the timing advance data. Thereafter it obtainsradio condition measurement data in the form of cell load measurements,step 38, which are typically uplink interference measurements. Theservice requirement obtaining unit 32 obtains service requirements ofthe mobile stations. This may include data about required delay and/orrequired bit rate, i.e. a desired throughput. The data from both theseunits are then forwarded to the transmission attempt determining unit34, which goes on and decides if the transmission attempt target, in thefollowing also denoted target TA, is to be adjusted or not, step 42, andif this is not the case the power control functionality of the basestation is informed that no change is to be made. Thereafter thetransmission attempt determining unit 34 returns and obtains new radiocondition measurement data, step 36, and service requirement data (ifthis has changed), step 38. If however the unit 34 determines that achange should be made, step 42, it then determines the direction ofchange, i.e. if there is to be an increase or a decrease, step 44. Whenthis has been done the new value or possibly an offset for the pre-settarget is supplied as a signal C to the power control functionality ofthe base station, and here to the outer-loop power control unit, step46. Thereafter the power control unit may adapt the TA target setaccording to HARQ with the change provided by the control signal C inorder to obtain the desired link quality.

Furthermore, to optimize the system performance when handling delaysensitive users, a minimum transmission attempt target could be defined(TA_(min)), since it at some point may be suboptimal to reduce the delayfurther.

A decision to increase the target TA may here be based on facts like ifa mobile station has many consecutive transmission blocks that requiremore transmission attempts than the original target TA, or the mobilestation does not utilize the provided grant (bit rate), or that the usedtransmission block size given a high uplink interference isunfavourable.

A decision to decrease the target may be based on facts like that amobile station uses a large transmission block size and asks for more,while the system has spare resources, for instance because of low uplinkinterference. It may also be based on a temporary increase in SIR orbased on trial and error.

In this way it is possible to adjust the transmission targets TA for thecell. Such targets may be determined on a mobile station to mobilestation basis, i.e. independently for each mobile station communicatingwith the cell. However it is also possible to determine a total valuefor all mobile devices of the cell as well as for different groups ofmobile stations. When this is done for different groups, mobile stationsmay for instance be grouped according to service requirements so thatmobile stations having for instance a requirement of limited delay arein one group, while mobile stations having less severe delayrequirements, like chatting services are in another group, whilemessaging or file transfer having virtually no delay requirements may bein a third group. It is also possible to apply the same principles forbit rate requirements as well as to combine these. File transfer do forinstance have a high bit rate requirement, while semi-interactiveservices like chat has a more limited bit rate requirement. In this wayit is possible to provide differentiated targets for different groupsand in this way the efficiency of the whole cell may be raised. Otherways to use the present invention is to have different targets perservice, per cell or per system.

Now a version of the method that is more suitable when determiningtransmission attempt targets when a low delay is a major concern will bedescribed with reference also being made to FIG. 5, which shows a flowchart of a number of method steps taken according to a first variationof the present invention in order to adjust the targeted number oftransmission attempts in the target TA.

Also this method may be applied singly or jointly for a group of mobilestations, where the group may include all mobile stations or just some,for instance the ones having a requirement of a small delay. In thedescription below focus will be on a single mobile station.

The radio condition measurement obtaining unit 30 of the transmissionattempt determining device 22 first obtains radio condition measurementsin the form of load measurements, step 48, which are normallymeasurements on the uplink interference. These are then compared by thetransmission attempt determining unit 34, with a first low loadthreshold T1. If the interference is below this threshold T1, step 50,which indicates that the interference is low, the transmission attemptdetermining unit 24 then obtains further radio condition measurementsfrom the radio condition measurement obtaining unit 30, step 52. Thesemeasurements include measurements relating to transmission power in theform of code power CP, the signal to carrier interference (SIR) targetand the path gain. The transmission attempt determining unit 34 thencompares these measurements with certain criteria indicative ofacceptable radio conditions. These criteria are not fulfilled if thecode power is above a first code power threshold, which thresholdindicates a high code power, if the power does not meet the signal tocarrier interference (SIR) target or if the path gain is bad. A highcode power here indicates that the mobile station may be located closeto the edge of the cell. An alternative to investigating code power isthe power headroom. It is furthermore also possible to investigatetiming advance for determining if a mobile station is close to the edgeof a cell. Other ways to determine if a mobile station is close to theedge of a cell are through obtaining position data associated withpositioning units in the mobile stations, like GPS units, or throughtriangulation via a number of base stations. When the criteria are notfulfilled, step 53, for the cases of a high code power, inability tomeet SIR or a bad path gain, a possible increase of the TA target iscontemplated. However, before this can be implemented it has to bedetermined if the service requirements allow such an increase, forinstance for VoIP applications. An increase of the target will lead to ahigher delay, which might not be allowed. Therefore the transmissionattempt determining unit 34 obtains the service requirements via theservice requirement obtaining unit 32 and consults them, step 54. If theservice requirements allow it, step 56, an increase in the target TA ismade, step 58. If an increase is not allowed, step 56, the target TA iskept unchanged, step 75.

If the criteria were not fulfilled, step 53, an investigation is made ifthe code power is below a second lower code power threshold. The secondcode power threshold indicates that low power is used and that themobile station 16 should be close to the base station 10. Also heretiming advance and power headroom is an alternative to code power.Therefore, when on the other hand the comparison of the code power CPwith the second code power threshold indicates that the code power CP isabove the second threshold, step 60, there is also no change in the TAtarget, step 75, while if it is below the second threshold, step 60,this indicates that the mobile station 16 should be close to the basestation 10 and that the target may be lowered. If the code power waslow, step 60, the service requirements are again considered, step 62,and if they allow it, step 63, the target is decreased, step 64, whileif they do not allow it, step 63, the target is kept unchanged, step 75.Instead of or in addition to consulting the service requirements in step62, it is possible to compare the contemplated target decrease with aminimum target value and refrain from decreasing the target if it willend up below this minimum target value.

If the load was not below the first load threshold, step 50, it iscompared with a second high load threshold T2, which indicates a highload. If the load on the cell was not above this second threshold, step66, then the target is kept unchanged, step 75. If however, the load wasabove the threshold T2, step 66, then once again further radio conditionmeasurements are obtained, step 68. These measurements as before includemeasurements relating to code power CP, the signal to carrierinterference (SIR) target and the path gain. These are then comparedwith the same radio condition criteria as mentioned before. If thecriteria are fulfilled, step 70, then the target is kept unchanged, step75, while If the criteria were not fulfilled, step 70, an increase inthe target is considered. However, before this is done the servicerequirements are again consulted, step 71. If the service requirementsallow it, step 72, an increase in the target TA is made, step 74. If anincrease was not allowed, step 72, the target TA is kept unchanged, step75.

The above mentioned steps may then be repeated continuously for thecell.

The above mentioned method may with advantage be applied for mobilestations requesting services that have low delay requirements, such asVoIP services.

Now a version of the method that is more suitable when determiningtransmission attempt targets when a high bit rate or high throughput isa major concern will be described with reference being made to FIG. 6,which shows a flow chart of a number of method steps taken according toa second variation of the present invention in order to adjust thetargeted number of transmission attempts. It should however be realisedthat this variation may also be used where delay is an issue.

In the method a desired TA target and a maximum TA target are set, whileuplink interference and used E-TFC are monitored. E-TFC (E-DCH TransportFormat Combination) in essence provides a measure of a selection by amobile station of the amount of data that is to be transmitted within acertain time interval with the transmit power that is available.

The method starts with the obtaining of information relating to theE-TFC from a mobile station, step 76, which is thus a measure of thedata block size. E-TFC can also be seen as a transmission block sizerelated value. Thereafter the service requirements are consulted, step78, and here the bit rate requirements possibly together with the delayrequirements. These requirements together with the current TA targetgives a minimum required E-TFC which is needed to fulfil the bit raterequirement. Thereafter it is investigated if the E-TFC is below a thirdthreshold T3, step 80. This threshold is here set such that thethreshold is exceeded only for the maximum E-TFC. If the threshold isnot exceeded, step 80, the TA value is increased, step 82, while if itis exceeded, step 80, load measurements are obtained, step 84, normallyin the form of uplink interference measurements. The load measurementsare then compared with a load threshold T4, which is set to a maximuminterference. If this threshold T4 is then not exceeded, step 86, the TAtarget is decreased, step 88, while if the threshold is exceeded, thetarget TA is kept unchanged, step 90.

The second described variation of the present invention may withadvantage be combined with the first described variation in that thefirst variation is used mainly for mobile stations having delaylimitations, for instance when they use VoIP services, while the secondvariation is provided mainly for mobile stations having certain bit raterequirements. When this is done the investigation regarding therequirement for a minimum E-TFC may be omitted in the second variation.

The present invention has many advantages. It adapts the targeted numberof transmission attempts based on the load on a cell, the servicerequirements as well as the location of a mobile station within thecell. In this way a better compromise is reached between the desire ofthe user (mobile station) and the restrictions of the network. Ittherefore increases user throughput by adopting to low delay primarilyfor a user close to a base station, it increases system capacity andstability when users are far away from the base station, i.e. it doesnot waste system capacity by providing unnecessary and/or ineffectivelow delay to cell-border users, it increases the system capacity for lowbit rate services (e.g. VoIP) due to adopting the SIR-target change tothe service requirements and it increases the system capacity on a longterm by adapting the E-DPDCH (E-DCH Dedicated Physical Data Channel)power offset to the user and cell situation.

The transmission attempt determining device according to the presentinvention can be implemented through one or more processors togetherwith computer program code for performing the functions of theinvention. The program code mentioned above may also be provided as acomputer program product, for instance in the form of a data carriercarrying computer program code for performing the method according tothe present invention when being loaded into a computer. Thetransmission attempt determining device may furthermore be provided as aseparate device or as a part of another entity in the network, such as apart of a communication control device, such as a base station or aradio network controller. The control signal mentioned above is notlimited to be provided to an outer loop-control unit, but can besupplied to any power control unit where transmission attempts are made.

While the invention has been described in connection with what ispresently considered to be most practical and preferred embodiments, itis to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements. Therefore the presentinvention is only to be limited by the following claims.

1. A method of adjusting a targeted number of transmission attempts inuplink communications between a group of mobile stations and a cell in awireless network, comprising: obtaining measurement data of radioconditions of uplinks between mobile stations in the group and the cell;obtaining service requirement data for mobile stations in the group;determining, based on obtained data, whether to adjust the targetednumber of transmission attempts that can be made by mobile stations inthe group in order to obtain a desired link quality for each uplink; andif it is determined to adjust the targeted number, determining based onthe obtained data whether to increase or to decrease the targetednumber, and adjusting the targeted number accordingly.
 2. The method ofclaim 1, wherein obtaining measurement data comprises obtaining dataindicative of a load on the cell.
 3. The method of claim 1, whereinwhether to adjust the targeted number is determined separately for eachmobile station of the at least one first group.
 4. The method of claim1, wherein whether to adjust the targeted number is determined jointlyfor all mobile stations in the group.
 5. The method of claim 1, whereina service requirement for the group comprises a maximum delay.
 6. Themethod of claim 5, wherein the radio conditions include transmissionpower, and a decrease of the targeted number is determined if themeasurement data of transmission power is below a lower transmissionpower threshold and if a load on the cell is below a low-load threshold.7. The method of claim 6, wherein the measurement data of the radioconditions are compared with criteria indicative of acceptable radioconditions, and an increase of the targeted number is determined ifallowed by a delay requirement and if the load is below the low-loadthreshold or above a high-load threshold.
 8. The method of claim 1,wherein a service requirement for the group comprises a required bitrate.
 9. The method of claim 8, wherein the measurement data comprises avalue related to transmission block size.
 10. The method of claim 9,wherein an increase of the targeted number is determined if the valuerelated to transmission block size is below a maximum level.
 11. Themethod of claim 9, wherein a decrease of the targeted number isdetermined if the value related to transmission block size equals amaximum level and if a load on the cell is below a load threshold.
 12. Adevice for determining transmission attempts to a cell in a wirelessnetwork from a group of mobile stations, comprising: a radio measurementunit configured to obtain measurement data of radio conditions ofuplinks between mobile stations of the group and the cell; a servicerequirement unit configured to obtain service requirement data formobile stations of the group; and a transmission attempt unit configuredto determine, based on obtained data, whether to adjust a targetednumber of transmission attempts that can be made by mobile stations inthe group in order to obtain desired link qualities for the uplinks; ifit is determined to adjust the targeted number, to determine, based onthe obtained data, whether to increase or to decrease the targetednumber; and to supply a control signal indicative of an adjustedtargeted number.
 13. The device of claim 12, wherein the device isincluded in a communication control device.
 14. The device of claim 13,wherein the communication control device is a cell handling device. 15.The device of claim 13, wherein the communication control device is aradio network controller.